We
are currently featuring the Eugene Dietzgen Co. at
Crate's Quality Slide Rules:

A Tribute to the Eugene
Dietzgen Co.

Dietzgen published numerous evocative
ads in popular magazines, celebrating the Romance of New
Technologies ...

The following ad ran in 1954. Times have changed.

I date this one from the mid-'50's:

A Dietzgen catalog from 1942:

The artwork was distinctive, even on
the manuals:

We mustn't forget the slide rules!

Below: Polymath Multiplex
Decimal Trig Type Cat. No. 1744

(How did they thought up those names?)

And, one of the most lovely slide rules
ever created ...

The Dietzgen-Tyler Multilog

Lousy indicator design, though.

- 1939 catalog -

An interesting process, obsolescence -
but, what does it mean, really? These old things are no longer deemed
useful. However, they still have value, perhaps of another kind.
Really, they're just as useful as before, they haven't gotten "worse"
at doing what they do - but if we know of something else that does the
job "better", it seems we are compelled to abandon our old, faithful
tools. Upgrade we must!

Click on the picture to visit Dietzgen's own history webpage.
(No they won't sell you any slide rules, I've already tried!)

Special Topics

Where we discuss:

Interesting, and Rather
Unusual,

but Somewhat Obscure,

Slide
Rules

The Hemmi #256

These instructions are for a Hemmi slide
rule designed for problems in Electrical Communications. As most slide
rules have a common set of scales, one can generally get by without a
manual, or with a manual from another model rule. However, this
approach is of no use in the case of the Hemmi 256. Thus, I am
propagating the contents of a fairly ancient manual on the subject
which was most graciously supplied by Mr. Cyril Catt of Lambton North,
Australia.

Transcription of section: Calculation
of Resonant Frequency.

Resonant frequency of electric
current with inductance L and capacitance C is expressed by: F =
1/(2*Pi*Sqrt(L*C)), where "Sqrt" denotes square root and "Pi" is the
famous ratio of a circle's diameter to its circumference. This kind of
calculation is done with the use of the L, C' and F scales. Symbolic
law of decimal point placement: F=L+C' (this determines the exponent or
power of 10 of the answer. The scales selected for L and C have
accompanying numbers, in red, to determine the exponent. These numbers
are summed and subsequently used to find exponent of frequency)Example: find the resonant frequency for a circuit
if L = 7 microhenries, C = 50 picofarads.Method: Set the red line F of the scale to 7
microhenries on the L scales. Set indicator to 50 pF on the C' scale,
under the hairline read 85 on the scale F. According to the symbolic
law of decimal point placement, from F=0+1=1, answer is found as 8.5
mc/s.

"KERCS" Project

I am now able to report encouraging news
for sufferers of KERCS (K+E Rotting Cursor Syndrome). KERCS is a
non-infectious but devastating malady endemic to 30's era K+E that were
supplied with cursor guides composed of cellulose nitrate, a plastic
with poor aging properties. After a few decades, the guides crumble and
the cursor fall apart, leaving behind a beautiful but useless, slide
rule. Now, working in collaboration with a California firm, we have
developed prototypes of replacements for these pieces, made of modern,
high-tech materials with better aging properties and close color and
opacity matches. It is expected that these "K+E replacement cursor
guides" will soon be available to the general public for a modest
consideration. We will endeavor to keep you informed in the column. It
would be appreciated if potentially interested parties would let us
know of any interest at an early time.

KERCS Update (6-6-06)

They have finally arrived. Sets are
available for $75. This includes both guides, eight tiny screws, and
all shipping and related costs (they're small!). The material we
selected is not as close a match as expected to the original color; it
looked darker before it was cut into pieces! However, the parts are
beautiful: one is etched with "KEUFFEL + ESSER CO. N.Y.", and the other
with "PATENT 2,0862502". These parts are extremely faithful
reproductions and will serve your slide rule well (even better than the
originals). Please be aware that the supply is limited.

The plastic parts are milled on a
numerically-controlled machine tool, drilled and tapped for the screws
and then laser-etched with the lettering. The spring is then riveted
on. Each piece is hand-finished.

Below is a photo of the prototypes:

And here is a photo of the production
version:

A New KERCS Development: Reproduction
K+E Indicator Frames (5-25-00)

We are being assisted in our effort to
provide accurate reproductions of K+E indicator pieces by the former
plant manager of the K+E plant in Connecticut. He presided over the
shutting down of the K+E Slide Rule manufacturing operation there. He
is redeeming himself now, however, by guiding us in the recreation of
the indictor frames. We will be turning out a prototype in the next few
months.

K+E Indicator Frames Update (9-2-02)

This project has undergone an indefinite
delay as my partner's wife is ill and he has not been possessed of
sufficient motivation to complete the prototypes.

Mathematical Digressions: the
ubiquitous number "e".

Part one: a tally of "e"-sightings.
(Please feel compelled to make a contribution. I am particularly
interested in original ideas, so please send me an "e"-mail with your
"e"-notion and I will post it with an attribution.)
1. Euler's famous equation for sinusoidal functions
2. The kernel of Gaussian functions (which are, in turn, components of
all eigenfunctions of Fourier Transforms).
e. "e" raised to a power is an (the only) eigenfunction of the
derivative operator.
3. e is even implicated in the ratio of prime to non-prime numbers.
(Hadamard - the ratio of non-prime to prime numbers approaches a
finction of 'e', as the numbers involved go to infinitity.)

A reasonable question! It seems that
slide rules represent, for me, the optimal collector's item in that
they are found at the intersection of three rather synergistic realms:
1. Aesthetics: many of them are works of technical art - wood, engraved
and paint-filled celluloid, metal and glass - they possess the beauty
of fine tools. 2. Mathematics - they teach a lot about math if one
troubles to learn to use it - and on a wonderfully physical level. 3.
Rarity - slide rules are at the wonderful time in their history when no
one makes them (as far as I know) but there are still a fair number
around and the people that remember using them are still around, too.
It's fun! And I find that the people that appreciate them tend to be of
a rather nice sort.